Polycythemia

Group C: Melanie, Michele, Sarah

Polycythemia

Polycythemia is an increase in RBC production (erythrocytosis) and can be relative or absolute (McCance & Huether, 2006). This causes the blood to become more viscous and can predispose a patient to thrombosis (Merck, 2005).

Relative Polycythemia: is a temporary condition related to dehydration. It typically affects obese, hypertensive individuals but can be corrected with adequate fluid resuscitation

Absolute Polycythemia: is a chronic condition that results from abnormal bone marrow stem cells. It can be primary (also known as Polycethemia Vera) or secondary.

(McCance & Huether, 2006)

Polycythemia Vera (PV) is a chronic non malignant condition characterized by an increased production of RBC’s, WBC’s and platelets. RBC production increases independently of erythroipoietin. Blood volume expands, becomes more viscous and has the potential to cause a thrombus. Platelet dysfunction may occur and increase the risk of bleeding. Depending on treatment PV can transform into acute Leukemia.

(Merck, 2005)

Criteria for Diagnosis of Polycythemia VeraErythrocytosis, absence of secondary polycythemia, and characteristic bone marrow changes (panmyelosis, enlarged megakaryocytes with clumping)

Plus any of the following:SplenomegalyPlasma erythropoietin level < 4 mUnits/mLPlatelet count > 400,000 μLPositive endogenous coloniesIn the absence of infection, neutrophil count >

10,000/μLA clonal cytogenetic abnormality in the marrow(Merck, 2005).

Secondary Polycythemia is more common and is caused by an increase in erythropoietin. This increase in erythropoietin can be caused by an erythropoietin-secreting tumour or as a normal physiological response to chronic hypoxia such as:

lung disease (COPD), high altitude, intracardiac shunts, hypoventilation syndromes, abnormal Hb, smoking-induced carboxyhemoglobinemia(Merck, 2005).

ThrombocytopeniaThrombocytopenia is a platelet count

below 100,000/mm3 of blood. As the platelet count drops the risk of hemorrhage increases. Spontaneous bleeding can occur with a count less than 15,000. In an individual with a count less than 10,000 severe bleeding can occur and can be fatal if it occurs in the GI tract, Respiratory system or the CNS.

(McCance and Huether, 2006)

Spontaneous bleeding can result in petechiae, ecchymoses, large purpuric spots, or bleeding from mucous membranes (McCance and Huether, 2006). It can also cause blood in urine, stool and prolonged and heavy menses. The can also be prolonged bleeding with any cut or profuse bleeding with surgery or procedure (MayoClinic,2008).

Petechiae (taken from MayoClinic.com)

Thrombocytopenia can occur due to immunologic and nonimmunologic causes.

Immunologic causes include:◦Immune thrombocytopenic purpura (ITP)◦Post blood transfusion◦Viral infection (HIV, EBV, CMV, rubella)◦Connective tissue (SLE) or

lymphoproliferative diseases

Nonimmunologic causes:

Gram negative sepsisAcute Respiratory Distress SyndromeDrug induces (Quinidine, Sulfa

preparations, carbamazepine, methyldopa, ASA, Oral antidiabetic drugs, gold salts, rifampin and heparin, chemo agents).

(Merck, 2005)

Immune Thrombocytopenic Purpura (ITP)

In ITP autoantibody target platelet glycoproteins. The platelets coated with antibodies are removed from circulation by phagocytes in the spleen resulting in a decrease in circulating platelets. The autoantibodies are also thought to affect platelet development within bone marrow.

(McCance & Huether, 2006)

Thrombotic Thrombocytopenic Purpura (TTP)

TTP is a manifestation of thrombocytopenia in which platelets aggregate to form occlusions affecting the small arteries and capillaries of the microcirculation. The thrombi formed are composed mostly of platelets with minimal fibrin and red cells.

Chronic relapsing TTP: is a rare form more commonly seen in children

Acute idiopathic TTP: more common, severe type that can rapidly become fatal.

TTP

Chronic relapsing TTP: is a rare form more commonly seen in children

Acute idiopathic TTP: more common, severe type that can rapidly become fatal. Pts have severe thrombocytopenia, hemolytic anemia and develop signs of ischemia related to CNS involvement.

(McCance & Huether, 2006)

References:MayoClinic (2008). Diseases and Conditions: Thrombocytopenia (low

platelet count). Retrieved Febuary 17th 2009 from:

http://www.mayoclinic.com/health/thrombocytopenia/DS00691/DSECTION=symptoms

McCance, K.L., & Huether, S.E. (2006). Pathophysiology: The Biologic Basis for Disease in Adults and Children (5th ed.). St. Louis: Elsevier Mosby.

Merck (2005). Thrombocytopenia. Retrieved February 14th 2009 from: http://www.merck.com/mmpe/sec11/ch133/ch133f.html.

Merck (2005). Polycethemia Vera. Retrieved February 14th 2009 from: http://www.merck.com/mmpe/sec11/ch141/ch141d.html.

Photo of RBC’s retrieved February 13th 2009 from: http://www.internetphotos.net/red-blood-cells-photo.html